Twin Towers collapse after September 11 attack. Illustration showing the South Tower (left, smoke and debris) of the World Trade Center in New York City, USA, collapsing following the September 11 attacks. Two passenger planes were hijacked by terrorists and flown into the North and South Towers. They impacted the North Tower (right) at 08:46 and South Tower at 09:03. The structural damage caused by the impacts and fires that broke out in the buildings caused them to collapse at 09:59 (South Tower) and 10:28 (North Tower). Many people evacuated safely, but 2763 in the buildings and the surrounding area were killed.